What is the difference between the Favorite and Favorite+ folders?

If you add a folder to Favorite, you can see the folder in the left main menu and you can access the folder more easily.
If you add a folder as Favorite+, the sub folders are included. Thus, you can see the emails in the folder and the sub folders together in the same mail list.

• Favorite: Adds the current folder to your Favorites
• Favorite+: Adds the current folder including sub folders to your Favorites